Proto-oncogene PIM-1 is a novel estrogen receptor target associating with high grade breast tumors

Macrocyclization strategy for improving candidate profiles in medicinal chemistry

Macrocycles are defined as cyclic compounds with 12 or more members. In medicinal chemistry, they are categorized based on their core chemistry into cyclic peptides and macrocycles. Macrocycles are advantageous because of their structural diversity and ability to achieve high affinity and selectivity towards challenging targets that are often not addressable by conventional small molecules. The potential of macrocyclization to optimize drug-like properties while maintaining adequate bioavailability and permeability has been emphasized as a key innovation in medicinal chemistry. This review provides a detailed case study of the application of macrocyclization over the past 5 years, starting from the initial analysis of acyclic active compounds to optimization of the resulting macrocycles for improved efficacy and drug-like properties. Additionally, it illustrates the strategic value of macrocyclization in contemporary drug discovery efforts.

Integrative modeling uncovers p21-driven drug resistance and prioritizes therapies for PIK3CA-mutant breast cancer

Utility of PI3Kα inhibitors like BYL719 is limited by the acquisition of genetic and non-genetic mechanisms of resistance which cause disease recurrence. Several combination therapies based on PI3K inhibition have been proposed, but a way to systematically prioritize them for breast cancer treatment is still missing. By integrating published and in-house studies, we have developed in silico models that quantitatively capture dynamics of PI3K signaling at the network-level under a BYL719-sensitive versus BYL719 resistant-cell state. Computational predictions show that signal rewiring to alternative components of the PI3K pathway promote resistance to BYL719 and identify PDK1 as the most effective co-target with PI3Kα rescuing sensitivity of resistant cells to BYL719. To explore whether PI3K pathway-independent mechanisms further contribute to BYL719 resistance, we performed phosphoproteomics and found that selection of high levels of the cell cycle regulator p21 unexpectedly promoted drug resistance in T47D cells. Functionally, high p21 levels favored repair of BYL719-induced DNA damage and bypass of the associated cellular senescence. Importantly, targeted inhibition of the check-point inhibitor CHK1 with MK-8776 effectively caused death of p21-high T47D cells, thus establishing a new vulnerability of BYL719-resistant breast cancer cells. Together, our integrated studies uncover hidden molecular mediators causing resistance to PI3Kα inhibition and provide a framework to prioritize combination therapies for PI3K-mutant breast cancer.

Photoinduced electron transfer (PeT) based fluorescent probes for cellular imaging and disease therapy

Typical PeT-based fluorescent probes are multi-component systems where a fluorophore is connected to a recognition/activating group by an unconjugated linker. PeT-based fluorescent probes are powerful tools for cell imaging and disease diagnosis due to their low fluorescence background and significant fluorescence enhancement towards the target. This review provides research progress towards PeT-based fluorescent probes that target cell polarity, pH and biological species (reactive oxygen species, biothiols, biomacromolecules, etc.) over the last five years. In particular, we emphasise the molecular design strategies, mechanisms, and application of these probes. As such, this review aims to provide guidance and to enable researchers to develop new and improved PeT-based fluorescent probes, as well as promoting the use of PeT-based systems for sensing, imaging, and disease therapy.

Antitumor activity of the protein kinase inhibitor 1-(β-D-2'-deoxyribofuranosyl)-4,5,6,7-tetrabromo- 1H-benzimidazole in breast cancer cell lines

Background

The protein kinases CK2 and PIM-1 are involved in cell proliferation and survival, the cell cycle, and drug resistance, and they are found overexpressed in virtually all types of human cancer, including breast cancer. In this study, we investigated the antitumor activity of a deoxynucleoside derivative, the protein kinase inhibitor compound 1-(β-D-2′-deoxyribofuranosyl)-4,5,6,7-tetrabromo-1H-benzimidazole (K164, also termed TDB), inter alia CK2 and PIM-1, on breast cancer cell lines (MDA-MB-231, MCF-7, and SK-BR-3).

Methods

An evaluation of the cytotoxic and proapoptotic effects, mitochondrial membrane potential (ΔΨm), and cell cycle progression was performed using an MTT assay, flow cytometry, and microscopic analysis. The Western blotting method was used to analyze the level of proteins important for the survival of breast cancer cells and proteins phosphorylated by the CK2 and PIM-1 kinases.

Results

The examined compound demonstrated the inhibition of cell viability in all the tested cell lines and apoptotic activity, especially in the MCF-7 and SK-BR-3 cells. Changes in the mitochondrial membrane potential (ΔΨm), cell cycle progression, and the level of the proteins studied were also observed.

Conclusions

The investigated CK2 and PIM-1 kinase inhibitor K164 is a promising compound that can be considered a potential agent in targeted therapy in selected types of breast cancer; therefore, further research is necessary.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10156-8.

Design, synthesis, and bioactivity evaluation of macrocyclic benzo[b]pyrido[4,3-e][1,4]oxazine derivatives as novel Pim-1 kinase inhibitors

Pim-1 kinase is a serine/threonine kinase which is vital in many tumors. The Pim-1 inhibitor 10-DEBC and its derivatives discovered in our previous work were modified through macrocyclization strategy. A series of benzo[b]pyridine[4,3-e][1,4]oxazine macrocyclic compounds were designed, synthesized, and evaluated as novel Pim-1 kinase inhibitors. Among these compounds, compound H5 exhibited the highest activity with an IC₅₀ value of 35 nM. In addition, the crystal complex structure of Pim-1 kinase bound with compound H3 was determined, and the structure-activity relationship of these macrocyclic compounds was analyzed, which provides the structural basis of further optimization of novel macrocyclic Pim-1 kinase inhibitors..

PIM1/STAT3 axis: a potential co-targeted therapeutic approach in triple-negative breast cancer

Triple-negative breast cancer lacks an expression of ER, PR, and Her-2, has a poor prognosis, and there are no target therapies available. Therapeutic options to treat TNBC are limited and urgently needed. Strong evidence indicates that molecular signaling pathways have a significant function to regulate biological mechanisms and their abnormal expression endows with the development of cancer. PIM kinase is overexpressed in various human cancers including TNBC which is regulated by various signaling pathways that are crucial for cancer cell proliferation and survival and also make PIM kinase as an attractive drug target. One of the targets of the STAT3 signaling pathway is PIM1 that plays a key role in tumor progression and transformation. In this review, we accumulate the current scenario of the PIM-STAT3 axis that provides insights into the PIM1 and STAT3 inhibitors which can be developed as potential co-inhibitors as prospective anticancer agents.

PIM-induced phosphorylation of Notch3 promotes breast cancer tumorigenicity in a CSL-independent fashion

Dysregulation of the developmentally important Notch signaling pathway is implicated in several types of cancer, including breast cancer. However, the specific roles and regulation of the four different Notch receptors have remained elusive. We have previously reported that the oncogenic PIM kinases phosphorylate Notch1 and Notch3. Phosphorylation of Notch1 within the second nuclear localization sequence of its intracellular domain (ICD) enhances its transcriptional activity and tumorigenicity. In this study, we analyzed Notch3 phosphorylation and its functional impact. Unexpectedly, we observed that the PIM target sites are not conserved between Notch1 and Notch3. Notch3 ICD (N3ICD) is phosphorylated within a domain, which is essential for formation of a transcriptionally active complex with the DNA-binding protein CSL. Through molecular modeling, X-ray crystallography, and isothermal titration calorimetry, we demonstrate that phosphorylation of N3ICD sterically hinders its interaction with CSL and thereby inhibits its CSL-dependent transcriptional activity. Surprisingly however, phosphorylated N3ICD still maintains tumorigenic potential in breast cancer cells under estrogenic conditions, which support PIM expression. Taken together, our data indicate that PIM kinases modulate the signaling output of different Notch paralogs by targeting distinct protein domains and thereby promote breast cancer tumorigenesis via both CSL-dependent and CSL-independent mechanisms.

Discovery of novel pyrazolo[3,4-b]pyridine scaffold-based derivatives as potential PIM-1 kinase inhibitors in breast cancer MCF-7 cells

Pim-1 kinase targeted recently has proved an essential goal of breast cancer therapy. We report the design, synthesis with full characterization analysis of pyrazolo[3,4-b]pyridine scaffold-based derivatives targeting Pim-1 kinase as anti-breast cancer agents. All the newly synthesized compounds were screened for their in vitro cytotoxic activity against two breast cancer cell lines MCF-7 and MDA-MB-231, and non-cancerous MCF-10A cells. Four derivatives notably, 17 and 19 exhibited a remarkable cytotoxic activity with IC₅₀ values 5.98 and 5.61 µM against MCF-7 (ERα-dependent) cells in a selective way, as they weren't active against MDA-MB-231 (non-ERα-dependent) and safe against MCF-10A. The most active compounds through in vitro screening were subjected to PIM-1 kinase to elucidate the Pim-1 kinase inhibitory activity as the mechanistic mode of action. Among the tested derivatives, Compounds 17 and 19 showed the highest inhibitory activity with IC₅₀ values 43 and 26 nM, respectively, compared to the 5-FU with IC₅₀ value 17 nM. Moreover, apoptotic investigation through flow cytometry and gene expression analysis of the apoptosis-related genes for the most active compound 19 against MCF-7. It was found that compound 19 induced apoptotic MCF-7 cell death by cell cycle arrest at G2/M phase and by elevation the expression of pro-apoptotic genes and inhibition of anti-apoptotic genes expression. Finally, the PIM-1 inhibition activities for compounds 17 and 19 were in accordance with the molecular docking study that revealed good interaction with the Pim-1 kinase active site.

Metabolic Imaging Detects Resistance to PI3Kα Inhibition Mediated by Persistent FOXM1 Expression in ER+ Breast Cancer

PIK3CA, encoding the PI3Kα isoform, is the most frequently mutated oncogene in estrogen receptor (ER)-positive breast cancer. Isoform-selective PI3K inhibitors are used clinically but intrinsic and acquired resistance limits their utility. Improved selection of patients that will benefit from these drugs requires predictive biomarkers. We show here that persistent FOXM1 expression following drug treatment is a biomarker of resistance to PI3Kα inhibition in ER+ breast cancer. FOXM1 drives expression of lactate dehydrogenase (LDH) but not hexokinase 2 (HK-II). The downstream metabolic changes can therefore be detected using MRI of LDH-catalyzed hyperpolarized 13C label exchange between pyruvate and lactate but not by positron emission tomography measurements of HK-II-mediated trapping of the glucose analog 2-deoxy-2-[18F]fluorodeoxyglucose. Rapid assessment of treatment response in breast cancer using this imaging method could help identify patients that benefit from PI3Kα inhibition and design drug combinations to counteract the emergence of resistance.

Regulation of insulin resistance and glucose metabolism by interaction of PIM kinases and insulin receptor substrates

Insulin resistance is caused by various environmental and genetic factors leading to a number of serious health issues. Due to its multifactorial origin, molecular characterization may provide better tools for its effective treatment. On molecular level, dysregulation of signaling pathway by insulin receptor substrates (IRSs) is one of the most common reasons of this disease. IRSs are regulated by >50 serine/threonine kinases, which may have positive or negative effects on insulin sensitivity. Among these serine/threonine kinases, PIM kinases have garnered much attention as they not only affect insulin sensitivity by phosphorylating IRSs directly and/or indirectly but also alter the activities of their downstream molecules like PI3K, AKT, and mTOR. In this review, interactions of PIM kinases with IRSs and their downstream proteins and their action mechanism in the regulation of insulin resistance are elaborated. Furthermore, this review offers fundamental understandings of the role of PIM kinases in this signaling pathway.

Combined inhibition of PIM and CDK4/6 suppresses both mTOR signaling and Rb phosphorylation and potentiates PI3K inhibition in cancer cells

Aberrant activation of mitogenic signaling pathways in cancer promotes growth and proliferation of cells by activating mTOR and S6 phosphorylation, and D-cyclin kinases and Rb phosphorylation, respectively. Correspondingly, inhibition of phosphorylation of both Rb and S6 is required for robust anti-tumor efficacy of drugs that inhibit cell signaling. The best-established mechanism of mTOR activation in cancer is via PI3K/Akt signaling, but mTOR activity can also be stimulated by CDK4 and PIM kinases. In this study, we show that the CDK4/6 inhibitor abemaciclib inhibits PIM kinase and S6 phosphorylation in cancer cells and concurrent inhibition of PIM, CDK4, and CDK6 suppresses both S6 and Rb phosphorylation. TSC2 or PIK3CA mutations obviate the requirement for PIM kinase and circumvent the inhibition of S6 phosphorylation by abemaciclib. Combination with a PI3K inhibitor restored suppression of S6 phosphorylation and synergized to curtail cell growth. By combining abemaciclib with a PI3K inhibitor, three pathways (Akt, PIM, and CDK4) to mTOR activation are neutralized, suggesting a potential combination strategy for the treatment of PIK3CA-mutant ER+ breast cancer.

Preclinical evaluation of a novel triple-acting PIM/PI3K/mTOR inhibitor, IBL-302, in breast cancer

The proviral integration of Moloney virus (PIM) family of protein kinases are overexpressed in many haematological and solid tumours. PIM kinase expression is elevated in PI3K inhibitor-treated breast cancer samples, suggesting a major resistance pathway for PI3K inhibitors in breast cancer, potentially limiting their clinical utility. IBL-302 is a novel molecule that inhibits both PIM and PI3K/AKT/mTOR signalling. We thus evaluated the preclinical activity of IBL-302, in a range of breast cancer models. Our results demonstrate in vitro efficacy of IBL-302 in a range of breast cancer cell lines, including lines with acquired resistance to trastuzumab and lapatinib. IBL-302 demonstrated single-agent, anti-tumour efficacy in suppression of pAKT, pmTOR and pBAD in the SKBR-3, BT-474 and HCC-1954 HER2+/PIK3CA-mutated cell lines. We have also shown the in vivo single-agent efficacy of IBL-302 in the subcutaneous BT-474 and HCC-1954 xenograft model in BALB/c nude mice. The combination of trastuzumab and IBL-302 significantly increased the anti-proliferative effect in HER2+ breast cancer cell line, and matched trastuzumab-resistant line, relative to testing either drug alone. We thus believe that the novel PIM and PI3K/mTOR inhibitor, IBL-302, represents an exciting new potential treatment option for breast cancer, and that it should be considered for clinical investigation.

PIM-1 kinase: a potential biomarker of triple-negative breast cancer

Triple-negative breast cancer is associated with a poor prognosis, and effective biomarkers for targeted diagnosis and treatment are lacking. The tumorigenicity of the provirus integration site for Moloney murine leukemia virus 1 (PIM-1) gene has been studied for many years. However, its significance in breast cancer remains unclear. In this review we briefly summarized the physiological characteristics and regulation of PIM-1 kinase, and subsequently focused on the role of PIM-1 in tumors, especially breast cancer. Oncogene PIM-1 was found to be upregulated in breast cancer, especially in triple-negative breast cancer. Moreover, it is involved in tumorigenesis and the development of drug resistance, and linked to poor prognosis. A highly selective probe targeting PIM-1 for imaging has emerged, suggesting that PIM-1 may be a potential biomarker for the accurate diagnosis and targeted therapy of triple-negative breast cancer.

PIM1 is responsible for IL-6-induced breast cancer cell EMT and stemness via c-myc activation

Background

Interleukin-6 (IL-6) has been demonstrated to be a critical factor for breast cancer malignancy. However, the molecular mechanisms by which IL-6 induce breast cancer cells epithelial–mesenchymal-transition (EMT) and stemness remain elusive.

Methods

Breast cancer cell lines T47D and MCF7 were exposed to IL-6, the expression of PIM1 was examined by quantitative real-time PCR (qRT-PCR) and western blot. Luciferase reporter assay was used to determine the transcriptional modulation of PIM1 by IL-6 and STAT3 inhibitor. Transwell assay was used to detect the invading ability of breast cancer cells induced by IL-6 or PIM1. The expressions of EMT and stemness markers were determined by qRT-PCR.

Results

IL-6 promoted PIM1 expression in a dose- and time-dependent manner, and this induction could be abrogated by inhibiting STAT3 activation, subsequently suppressing the transcriptional level of PIM1. Moreover, we noticed that knocking down of PIM1 in cells which was exposed to IL-6 significantly impaired the invasion ability and the expression of EMT and stemness markers. On the contrary, overexpression of PIM1 promoted cell invasion and upregulated the expression of EMT and stemness markers. In addition, we demonstrated that c-myc, the cofactor of PIM1, involved in the pro-oncogenic roles of PIM1. Knocking down of c-myc attenuated the PIM1-induced cell EMT and stemness.

Conclusion

This study proposed the upregulation of PIM1 by IL-6 contributed to breast cancer cell aggressiveness and targeting PIM1 or c-myc could be novel approaches for breast cancer treatment.

Expression of PIM-1 in salivary gland adenoid cystic carcinoma: Association with tumor progression and patients' prognosis

Pim-1 proto-oncogene, serine/threonine kinase (PIM-1) phosphorylates a series of substrates to exert its oncogenic function in numerous malignancies. The present study investigated the clinical significance of the PIM-1 protein, apoptosis status and apoptosis-associated proteins, including forkhead box O3a (FOXO3a), B cell lymphoma-2 (BCL-2) and BCL-2-associted agonist of cell death (BAD), were investigated in salivary gland adenoid cystic carcinoma (ACC) tissues. PIM-1 expression levels in 4 pairs of ACC tissues and corresponding normal salivary gland tissues were determined by western blot analysis. PIM-1, FOXO3a, BAD and BCL-2 expression levels in 60 ACC tissues were evaluated by immunohistochemistry (IHC). A terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling assay was performed to detect the apoptosis status of ACC tissues. PIM-1 was revealed to be highly expressed in ACC tissues compared with adjacent normal tissues. IHC staining results demonstrated high expression ratios of PIM-1, FOXO3a, BCL-2 and BAD [33.33% (20/60), 51.67% (31/60), 51.67% (31/60) and 55% (33/60)], respectively, and significant correlations between the expression of PIM-1 and FOXO3a and BCL-2 (P<0.05). Apoptotic rates were significantly associated with PIM-1, FOXO3a, BCL-2 and BAD expression levels (P<0.05). PIM-1 expression levels were significantly associated with tumor size, lymph node involvement, nerve invasion, distant metastasis and weakly associated with tumor node metastasis stage. Kaplan-Meier survival curves revealed that PIM-1 expression level was significantly associated with disease-free survival of patients with ACC (P=0.009). Cox regression multivariate analysis results revealed that histotype, distant metastasis and apoptotic rate were independent prognosis factors for ACC. Assessment of PIM-1 may be useful in investigating the malignant behaviors of ACC and predicting the outcome of patients with ACC.

Highly Selective Red-Emitting Fluorescent Probe for Imaging Cancer Cells in Situ by Targeting Pim-1 Kinase

Based on the fact that enzyme-targeting probes are highly sensitive and selective, a novel red-emitting probe (NB-BF) for Pim-1 kinase including three parts, fluorophore (NB), linker, and inhibitor (BF), has been designed for cancer optical imaging. In its free state, NB-BF is folded and the fluorescence quenched by PET between fluorophore and inhibitor both in PBS buffer and in normal cells. Significantly, it emitted strong red fluorescence in Pim-1 overexpressed cancer cells. The specificity of NB-BF for Pim-1 kinase was directly demonstrated by gene silencing analysis. Furthermore, it is the first time to know where Pim-1 kinase mainly distributes at mitochondria with Pearson's correlation factor (R_r) of 0.965 and to provide a fluorescent tool to verify the function of the Pim-1 kinase. More importantly, NB-BF was applied in tissue imaging and preferentially labeled tumors in vivo.

Phosphorylation of Notch1 by Pim kinases promotes oncogenic signaling in breast and prostate cancer cells

Tumorigenesis is a multistep process involving co-operation between several deregulated oncoproteins. In this study, we unravel previously unrecognized interactions and crosstalk between Pim kinases and the Notch signaling pathway, with implications for both breast and prostate cancer. We identify Notch1 and Notch3, but not Notch2, as novel Pim substrates and demonstrate that for Notch1, the serine residue 2152 is phosphorylated by all three Pim family kinases. This target site is located in the second nuclear localization sequence (NLS) of the Notch1 intracellular domain (N1ICD), and is shown to be important for both nuclear localization and transcriptional activity of N1ICD. Phosphorylation-dependent stimulation of Notch1 signaling promotes migration of prostate cancer cells, balances glucose metabolism in breast cancer cells, and supports in vivo growth of both types of cancer cells on chick embryo chorioallantoic membranes. Furthermore, Pim-induced growth of orthotopic prostate xenografts in mice is associated with enhanced nuclear Notch1 activity. Finally, simultaneous inhibition of Pim and Notch abrogates the cellular responses more efficiently than individual treatments, opening up new vistas for combinatorial cancer therapy.

Thyroid hormone inhibits growth of hepatoma cells through induction of miR-214

Thyroid hormone (TH) plays a role in regulating the metabolic rate, heart functions, muscle control and maintenance of bones. 3,3′5-tri-iodo-L-thyronine (T₃) displays high affinity to nuclear thyroid hormone receptors (TRs), which mediate most TH actions. Recent studies have shown hypothyroidism in patients with an increased risk of hepatocellular carcinoma (HCC). MicroRNAs (miRNAs), a class of non-protein-coding RNA, are suggested to control tumor growth by interacting with target genes. However, the clinical significance of T₃/TR-regulated miRNAs in tumors has yet to be established. In the current study, miRNA expression profile screening was performed using SYBR Green-Based qRT-PCR array in TR-overexpressing HepG2 cells. miR-214-3p, which is expressed at low levels in HCC, was stimulated upon T₃ application. The 3′UTR luciferase reporter assay confirmed that the proto-oncogene serine/threonine-protein kinase, PIM-1, is a miR-214-3p target. PIM-1 was decreased upon treatment with miR-214-3p or T₃ stimulation. PIM-1 was highly expressed in HCC, and the effect of PIM-1 on cell proliferation might be mediated by the inhibition of p21. Furthermore, the T₃-induced suppression of cell proliferation was partially rescued upon miR-214-3p knockdown. Our data demonstrate that T₃ induces miR-214-3p expression and suppresses cell proliferation through PIM-1, thus contributing to the inhibition of HCC tumor formation.

PIM1: a promising target in patients with triple-negative breast cancer

Triple-negative breast cancers (TNBCs) have poor prognosis, and chemotherapy remains the mainstay of therapy because of lack of discovered possible target. MYC were found overexpressed in TNBCs compared with other subtypes and especially in those resistant to chemotherapy, but the inhibition has been challenging to achieve. Recently, the cooperation of PIM1 and MYC was identified involved in cell proliferation, migration and apoptosis of TNBCs, which has been reported in hematological malignancy and prostatic cancer. Inhibition of PIM1 can promote the apoptosis of tumor cells and enhance sensitivity to chemotherapy. Notably, PIM1-null mice develop normally and are fertile, suggesting the side effects can be tolerated. Thus, PIM1 may be a promising target in TNBCs and further investigation, both in vivo and in vitro, needs to be carried out.

Biochemical changes of salivary gland adenoid cystic carcinoma cells induced by SGI-1776

Provirus integration site for Moloney murine leukemia virus 1 (Pim-1) has proved to be an oncogene and it is known that to depress Pim-1 activity may be a novel oncological treatment strategy. SGI-1776, a small molecule, is the first clinically tested inhibitor of the Pim kinase family. Here, we aimed to explore the effect of SGI-1776 on salivary adenoid cystic carcinoma (SACC). Expression of Pim-1 was confirmed in SACC and control tissues by qRT-PCR. After SGI-1776 treatment, the Pim-1 expressions and Pim-1 kinase activity in both SACC-83 and SACC-LM cell lines were measured. Cell proliferation, cell invasion, cell cycle, apoptosis and mitochondrial membrane potential were analyzed. Also, the expression of FOXO3a, p-FOXO3a, RUNX3, Bcl-2, BAD, p-BAD, Bim and p-Bim were detected by Western blot. The results showed that Pim-1 was significantly overexpressed in SACC tissues. SGI-1776 down-regulated the Pim-1 expression, inhibited Pim-1 kinase activity, reduced cell proliferation, decreased invasive ability, increased caspase-3 activity and induced apoptosis, cell cycle arrest and mitochondrial depolarization. Reduced expression was also seen in p-FOXO3a, RUNX3, Bcl-2, p-BAD and p-Bim, whereas no significant changes were observed from FOXO3a, BAD and Bim. These results confirm the pivotal role of Pim-1 in SACC and suggest that targeting Pim-1 kinase signal pathway by SGI-1776 might be a promising therapeutic modality for SACC.

PIM1 kinase inhibition as a targeted therapy against triple-negative breast tumors with elevated MYC expression

Triple-negative breast cancer (TNBC), in which cells lack expression of the estrogen receptor (ER), the progesterone receptor (PR) and the ERBB2 (also known as HER2) receptor, is the breast cancer subtype with the poorest outcome. No targeted therapy is available against this subtype of cancer owing to a lack of validated molecular targets. We previously reported that signaling involving MYC-an essential, pleiotropic transcription factor that regulates the expression of hundreds of genes-is disproportionally higher in triple-negative (TN) tumors than in receptor-positive (RP) tumors. Direct inhibition of the oncogenic transcriptional activity of MYC has been challenging to achieve. Here, by conducting a shRNA screen targeting the kinome, we identified PIM1, a non-essential serine-threonine kinase, in a synthetic lethal interaction with MYC. PIM1 expression was higher in TN tumors than in RP tumors and was associated with poor prognosis in patients with hormone- and HER2-negative tumors. Small-molecule PIM kinase inhibitors halted the growth of human TN tumors with elevated MYC expression in patient-derived tumor xenograft (PDX) and MYC-driven transgenic mouse models of breast cancer by inhibiting the oncogenic transcriptional activity of MYC and restoring the function of the endogenous cell cycle inhibitor, p27. Our findings warrant clinical evaluation of PIM kinase inhibitors in patients with TN tumors that have elevated MYC expression.

Epstein-Barr Virus: Diseases Linked to Infection and Transformation

Epstein–Barr virus (EBV) was first discovered in 1964, and was the first known human tumor virus now shown to be associated with a vast number of human diseases. Numerous studies have been conducted to understand infection, propagation, and transformation in various cell types linked to human diseases. However, a comprehensive lens through which virus infection, reactivation and transformation of infected host cells can be visualized is yet to be formally established and will need much further investigation. Several human cell types infected by EBV have been linked to associated diseases. However, whether these are a direct result of EBV infection or indirectly due to contributions by additional infectious agents will need to be fully investigated. Therefore, a thorough examination of infection, reactivation, and cell transformation induced by EBV will provide a more detailed view of its contributions that drive pathogenesis. This undoubtedly expand our knowledge of the biology of EBV infection and the signaling activities of targeted cellular factors dysregulated on infection. Furthermore, these insights may lead to identification of therapeutic targets and agents for clinical interventions. Here, we review the spectrum of EBV-associated diseases, the role of the encoded latent antigens, and the switch to latency or lytic replication which occurs in EBV infected cells. Furthermore, we describe the cellular processes and critical factors which contribute to cell transformation. We also describe the fate of B-cells and epithelial cells after EBV infection and the expected consequences which contribute to establishment of viral-associated pathologies.

PIM1 kinase regulates cell death, tumor growth and chemotherapy response in triple-negative breast cancer

Triple-negative breast cancers (TNBCs) have poor prognosis and lack targeted therapies. Here we identified increased copy number and expression of the PIM1 proto-oncogene in genomic data sets of patients with TNBC. TNBC cells, but not nonmalignant mammary epithelial cells, were dependent on PIM1 for proliferation and protection from apoptosis. PIM1 knockdown reduced expression of the anti-apoptotic factor BCL2, and dynamic BH3 profiling of apoptotic priming revealed that PIM1 prevents mitochondrial-mediated apoptosis in TNBC cell lines. In TNBC tumors and their cellular models, PIM1 expression was associated with several transcriptional signatures involving the transcription factor MYC, and PIM1 depletion in TNBC cell lines decreased, in a MYC-dependent manner, cell population growth and expression of the MYC target gene MCL1. Treatment with the pan-PIM kinase inhibitor AZD1208 impaired the growth of both cell line and patient-derived xenografts and sensitized them to standard-of-care chemotherapy. This work identifies PIM1 as a malignant-cell-selective target in TNBC and the potential use of PIM1 inhibitors for sensitizing TNBC to chemotherapy-induced apoptotic cell death.

Systematic Functional Characterization of Resistance to PI3K Inhibition in Breast Cancer

PIK3CA (which encodes the PI3K alpha isoform) is the most frequently mutated oncogene in breast cancer. Small-molecule PI3K inhibitors have shown promise in clinical trials; however, intrinsic and acquired resistance limits their utility. We used a systematic gain-of-function approach to identify genes whose upregulation confers resistance to the PI3K inhibitor BYL719 in breast cancer cells. Among the validated resistance genes, Proviral Insertion site in Murine leukemia virus (PIM) kinases conferred resistance by maintaining downstream PI3K effector activation in an AKT-independent manner. Concurrent pharmacologic inhibition of PIM and PI3K overcame this resistance mechanism. We also observed increased PIM expression and activity in a subset of breast cancer biopsies with clinical resistance to PI3K inhibitors. PIM1 overexpression was mutually exclusive with PIK3CA mutation in treatment-naïve breast cancers, suggesting downstream functional redundancy. Together, these results offer new insights into resistance to PI3K inhibitors and support clinical studies of combined PIM/PI3K inhibition in a subset of PIK3CA-mutant cancers.

SIGNIFICANCE

PIM kinase overexpression confers resistance to small-molecule PI3K inhibitors. Combined inhibition of PIM and PI3K may therefore be warranted in a subset of breast cancers. Cancer Discov; 6(10); 1134-47. ©2016 AACR.This article is highlighted in the In This Issue feature, p. 1069.

MicroRNA-124-3p regulates cell proliferation, invasion, apoptosis, and bioenergetics by targeting PIM1 in astrocytoma

The PIM1 protein is an important regulator of cell proliferation, the cell cycle, apoptosis, and metabolism in various human cancers. MicroRNAs (miRNAs) are powerful post‐transcriptional gene regulators that function through translational repression or transcript destabilization. Therefore, we aimed to identify whether a close relationship exists between PIM1 and miRNAs. PIM1 protein levels and mRNA levels were significantly upregulated in astrocytoma tissues, indicating the oncogenic role of PIM1 in astrocytoma. Further bioinformatics analysis indicated that miR‐124‐3p targeted the 3′‐UTR of PIM1. We also observed an inverse correlation between the miR‐124‐3p levels and PIM1 protein or mRNA levels in astrocytoma samples. Next, we experimentally confirmed that miR‐124‐3p directly recognizes the 3′‐UTR of the PIM1 transcript and regulates PIM1 expression at both the protein and mRNA levels. Furthermore, we examined the biological consequences of miR‐124‐3p targeting PIM1 in vitro. We showed that the repression of PIM1 in astrocytoma cancer cells by miR‐124‐3p suppressed proliferation, invasion, and aerobic glycolysis and promoted apoptosis. We observed that the restoration or inhibition of PIM1 activity resulted in effects that were similar to those induced by miR‐124‐3p inhibitors or mimics in cancer cells. Finally, overexpression of PIM1 rescued the inhibitory effects of miR‐124‐3p. In summary, these findings aid in understanding the tumor‐suppressive role of miR‐124‐3p in astrocytoma pathogenesis through the inhibition of PIM1 translation.

PIM1 polymorphism and PIM1 expression as predisposing factors of esophageal squamous cell carcinoma in the Asian population

Our study aimed to identify the association between a PIM1 polymorphism and PIM1 expression levels with clinicopathological features of esophageal squamous cell carcinoma (ESCC). A total of 168 patients with ESCC were recruited as the case group, and 180 healthy individuals were included as the control group. Polymerase chain reaction-direct sequencing was employed to analyze all genotypes containing the PIM1 -1 882 A>T mutation. Immunohistochemistry was used to detect PIM1 expression. The distributions of genotype AA and allele A of PIM1 -1 882 A>T were higher in the case group than in the control group (both P<0.05). AT + TT carriers had a lower risk of ESCC than AA carriers (P<0.05). PIM1 polymorphism was related to the invasion depth, degree of differentiation, and lymphatic metastasis of ESCC (P<0.05). PIM1 expression was associated with lymphatic metastasis of ESCC and PIM1 polymorphism (both P<0.05). PIM1 -1 882 A>T and the overexpression of PIM1 were associated with the clinicopathological features of ESCC, and PIM1 -1 882 A>T may help to reduce the risk of ESCC in the Asian population.

Recurrent CDK1 overexpression in laryngeal squamous cell carcinoma

In this study, we analyzed the expression profile of four genes (CCNA2, CCNB1, CCNB2, and CDK1) in laryngeal squamous cell carcinoma (LSCC) cell lines and tumor samples. With the application of microarray platform, we have shown the overexpression of these genes in all analyzed LSCC samples in comparison to non-cancer controls from head and neck region. We have selected CDK1 for further analysis, due to its leading role in cell cycle regulation. It is a member of the Ser/Thr protein kinase family of proven oncogenic properties. The results obtained for CDK1 were further confirmed with the application of reverse transcription quantitative polymerase chain reaction (RT-qPCR) technique, Western blot, and immunohistochemistry (IHC). The observed upregulation of CDK1 in laryngeal squamous cell carcinoma has encouraged us to analyze for genetic mechanisms that can be responsible this phenomenon. Therefore, with the application of array-CGH, sequencing analysis and two methods for epigenetic regulation analysis (DNA methylation and miRNA expression), we tried to identify such potential mechanisms. Our attempts to identify the molecular mechanisms responsible for observed changes failed as we did not observe significant alterations neither in the DNA sequence nor in the gene copy number that could underline CDK1 upregulation. Similarly, the pyrosequencing and miRNA expression analyses did not reveal any differences in methylation level and miRNA expression, respectively; thus, these mechanisms probably do not contribute to elevation of CDK1 expression in LSCC. However, our results suggest that alteration of CDK1 expression on both mRNA and protein level probably appears on the very early step of carcinogenesis.

Loss of PIM2 enhances the anti-proliferative effect of the pan-PIM kinase inhibitor AZD1208 in non-Hodgkin lymphomas

Background

A promising therapeutic approach for aggressive B-cell Non-Hodgkin lymphoma (NHL), including diffuse large B-cell lymphoma (DLBCL), and Burkitt lymphoma (BL) is to target kinases involved in signal transduction and gene regulation. PIM1/2 serine/threonine kinases are highly expressed in activated B-cell-like DLBCL (ABC-DLBCL) with poor prognosis. In addition, both PIM kinases have a reported synergistic effect with c-MYC in mediating tumour development in several cancers, c-MYC gene being translocated to one of the immunoglobulin loci in nearly all BLs.

Methods

For these reasons, we tested the efficiency of several PIM kinase inhibitors (AZD1208, SMI4a, PIM1/2 inhibitor VI and Quercetagetin) in preventing proliferation of aggressive NHL-derived cell lines and compared their efficiency with PIM1 and/or PIM2 knockdown.

Results

We observed that most of the anti-proliferative potential of these inhibitors in NHL was due to an off-target effect. Interestingly, we present evidence of a kinase-independent function of PIM2 in regulating cell cycle. Moreover, combining AZD1208 treatment and PIM2 knockdown additively repressed cell proliferation.

Conclusion

Taken together, this study suggests that at least a part of PIM1/2 oncogenic potential could be independent of their kinase activity, justifying the limited anti-tumorigenic outcome of PIM-kinase inhibitors in NHL.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0477-z) contains supplementary material, which is available to authorized users.

Nuclear Receptor Signaling Atlas: Opening Access to the Biology of Nuclear Receptor Signaling Pathways

Signaling pathways involving nuclear receptors (NRs), their ligands and coregulators, regulate tissue-specific transcriptomes in diverse processes, including development, metabolism, reproduction, the immune response and neuronal function, as well as in their associated pathologies. The Nuclear Receptor Signaling Atlas (NURSA) is a Consortium focused around a Hub website (www.nursa.org) that annotates and integrates diverse ‘omics datasets originating from the published literature and NURSA-funded Data Source Projects (NDSPs). These datasets are then exposed to the scientific community on an Open Access basis through user-friendly data browsing and search interfaces. Here, we describe the redesign of the Hub, version 3.0, to deploy “Web 2.0” technologies and add richer, more diverse content. The Molecule Pages, which aggregate information relevant to NR signaling pathways from myriad external databases, have been enhanced to include resources for basic scientists, such as post-translational modification sites and targeting miRNAs, and for clinicians, such as clinical trials. A portal to NURSA’s Open Access, PubMed-indexed journal Nuclear Receptor Signaling has been added to facilitate manuscript submissions. Datasets and information on reagents generated by NDSPs are available, as is information concerning periodic new NDSP funding solicitations. Finally, the new website integrates the Transcriptomine analysis tool, which allows for mining of millions of richly annotated public transcriptomic data points in the field, providing an environment for dataset re-use and citation, bench data validation and hypothesis generation. We anticipate that this new release of the NURSA database will have tangible, long term benefits for both basic and clinical research in this field.

DC-SCRIPT is a novel regulator of the tumor suppressor gene CDKN2B and induces cell cycle arrest in ERα-positive breast cancer cells

Breast cancer is one of the most common causes of cancer-related deaths in women. The estrogen receptor (ERα) is well known for having growth promoting effects in breast cancer. Recently, we have identified DC-SCRIPT (ZNF366) as a co-suppressor of ERα and as a strong and independent prognostic marker in ESR1 (ERα gene)-positive breast cancer patients. In this study, we further investigated the molecular mechanism on how DC-SCRIPT inhibits breast cancer cell growth. DC-SCRIPT mRNA levels from 190 primary ESR1-positive breast tumors were related to global gene expression, followed by gene ontology and pathway analysis. The effect of DC-SCRIPT on breast cancer cell growth and cell cycle arrest was investigated using novel DC-SCRIPT-inducible MCF7 breast cancer cell lines. Genome-wide expression profiling of DC-SCRIPT-expressing MCF7 cells was performed to investigate the effect of DC-SCRIPT on cell cycle-related gene expression. Findings were validated by real-time PCR in a cohort of 1,132 ESR1-positive breast cancer patients. In the primary ESR1-positive breast tumors, DC-SCRIPT expression negatively correlated with several cell cycle gene ontologies and pathways. DC-SCRIPT expression strongly reduced breast cancer cell growth in vitro, breast tumor growth in vivo, and induced cell cycle arrest. In addition, in the presence of DC-SCRIPT, multiple cell cycles related genes were differentially expressed including the tumor suppressor gene CDKN2B. Moreover, in 1,132 primary ESR1-positive breast tumors, DC-SCRIPT expression also correlated with CDKN2B expression. Collectively, these data show that DC-SCRIPT acts as a novel regulator of CDKN2B and induces cell cycle arrest in ESR1-positive breast cancer cells.

Targeting Pim kinases for cancer treatment: opportunities and challenges

Pim oncogenes are highly expressed in many types of hematological and solid cancers. Pim kinases regulate the network of signaling pathways that are critical for tumorigenesis and development, making Pim kinases the attractive drug targets. Currently, two approaches have been employed in designing Pim kinase inhibitors: ATP-mimetics and non-ATP mimetics; but all target the ATP-binding pocket and are ATP-competitive. In this review, we summarize the current progress in understanding the Pim-related structure and biology, and provide insights into the binding modes of some prototypical Pim-1 inhibitors. The challenges as well as opportunities are highlighted for development of Pim kinase inhibitors as potential anticancer agents.

Pim-1 acts as an oncogene in human salivary gland adenoid cystic carcinoma

Background

Pim-1 (Provirus integration site for Moloney murine leukemia virus 1) belongs to the Ser/Thr kinase family and plays a pivotal role in occurrence and development of oncogenesis. Recent studies have demonstrated that Pim-1 phosphorylates RUNX3 and alters its subcellular localization. However, few studies have concerned the implications of Pim-1 in the salivary gland adenoid cystic carcinoma (ACC). In this study, we aimed to clarify the function of Pim-1 in ACC in vitro. Meanwhile, we measured the levels of Pim-1 and RUNX3 in the ACC tissues. The correlations between Pim-1/RUNX3 levels and clinical parameters were also analyzed.

Methods

SACC-83 and SACC-LM cells were transfected with the Pim-1 siRNA. Pim-1 mRNA and protein expression were measured using real-time PCR and immnuoblot, respectively. Cell proliferation was analyzed by CCK-8 assay. Cell cycle, apoptosis, and mitochondrial membrane potential were detected by flow cytometry. Effects of Pim-1 on cells’ invasion were evaluated by transwell migration assay. Pim-1 and RUNX3 levels in ACC tissues were examined by immunohistochemistry.

Results

Pim-1 siRNA reduces cell proliferation, induces apoptosis, causes cell cycle arrest through cell cycle related proteins (Cyclin D1 and CDK4), mitochondrial depolarization, and decreases invasive ability in SACC-83 and SACC-LM cells. Pim-1 and RUNX3 levels are significantly relevant and associated with T-stage and nerve invasion in the ACC tissues.

Conclusions

This study demonstrates the oncogenic role of Pim-1 in ACC. The findings also suggest that Pim-1 may serve as a neoteric therapeutic target and potential prognostic marker for ACC cancer.

PIM kinases: an overview in tumors and recent advances in pancreatic cancer

The PIM kinases represent a family of serine/threonine kinases, which is composed of three different members (PIM1, PIM2 and PIM3). Aberrant expression of PIM kinases is observed in variety of tumors, including pancreatic cancer. The PIM kinases play pivotal roles in the regulation of cell cycle, apoptosis, properties of stem cells, metabolism, autophagy, drug resistance and targeted therapy. The roles of PIM kinases in pancreatic cancer include the regulation of proliferation, apoptosis, cell cycle, formation, angiogenesis and prediction prognosis. Blocking the activities of PIM kinases could prevent pancreatic cancer development. PIM kinases may be a novel target for cancer therapy.

The histone demethylase enzyme KDM3A is a key estrogen receptor regulator in breast cancer

Endocrine therapy has successfully been used to treat estrogen receptor (ER)-positive breast cancer, but this invariably fails with cancers becoming refractory to treatment. Emerging evidence has suggested that fluctuations in ER co-regulatory protein expression may facilitate resistance to therapy and be involved in breast cancer progression. To date, a small number of enzymes that control methylation status of histones have been identified as co-regulators of ER signalling. We have identified the histone H3 lysine 9 mono- and di-methyl demethylase enzyme KDM3A as a positive regulator of ER activity. Here, we demonstrate that depletion of KDM3A by RNAi abrogates the recruitment of the ER to cis-regulatory elements within target gene promoters, thereby inhibiting estrogen-induced gene expression changes. Global gene expression analysis of KDM3A-depleted cells identified gene clusters associated with cell growth. Consistent with this, we show that knockdown of KDM3A reduces ER-positive cell proliferation and demonstrate that KDM3A is required for growth in a model of endocrine therapy-resistant disease. Crucially, we show that KDM3A catalytic activity is required for both ER-target gene expression and cell growth, demonstrating that developing compounds which target demethylase enzymatic activity may be efficacious in treating both ER-positive and endocrine therapy-resistant disease.

Use of regulators and inhibitors of Pim-1, a serine/threonine kinase, for tumour therapy (review)

Pim-1 is a proto-oncogene that encodes a serine/threonine kinase that is overexpressed in a range of haematopoietic malignancies and solid cancers. Pim-1 expression is tightly regulated by multiple biomolecules at different levels. Several lines of evidence have indicated that dysregulation of Pim-1 can interfere with the cell cycle and apoptosis to promote malignant transformation of a number of types of tumour. Thus, investigation of Pim-1 regulation may provide important theoretical guidance for the development of molecular targeting therapies and drug treatments for Pim-1‑associated diseases. Regulators of Pim-1 expression, include microRNAs, oestrogen, inecalcitol, adenosine triphosphate (ATP) mimetic inhibitors and ATP competitive inhibitors of Pim-1. Combinations of inhibitors of Pim-1 expression and Pim-1‑specific inhibitors may provide novel therapies for cancer patients and directions for cancer treatment.

Expression of androgen receptor and its phosphorylated forms in breast cancer progression

BACKGROUND

Androgen receptor (AR) expression in breast cancers may serve as a prognostic and predictive marker. We examined the expression pattern of AR and its phosphorylated forms, Ser-213 (AR-Ser[P]-213) and Ser-650 (AR-Ser[P]-650), in breast cancer and evaluated their association with clinicopathological parameters.

METHODS

Immunohistochemistry was performed on primary and distant metastatic breast cancers and benign breast tissue using antibodies against AR, AR-Ser(P)-213, and AR-Ser(P)-650. The levels of cytoplasmic and nuclear expression were scored semiquantitatively using a histoscore.

RESULTS

Nuclear staining of AR was observed in all benign breast tissue and 67% of cancer cases. Nuclear and cytoplasmic AR-Ser(P)-213 was increased in breast cancers 2-fold (P = .0014) and 1.7-fold (P = .05), respectively, compared with benign controls, whereas nuclear and cytoplasmic AR-Ser(P)-650 expression was decreased in tumors by 1.9-fold and 1.7-fold (both P < .0001), respectively. Increased expression of nuclear or cytoplasmic AR-Ser(P)-213 was observed in metastatic breast cancers (1.3-fold, P = .05), ER-negative (2.6-fold, P = .001), and invasive ductal carcinoma (6.8-fold, P = .04). AR-Ser(P)-650 expression was downregulated in lymph node-positive breast cancers (1.4-fold, P = .02) but was upregulated in invasive ductal carcinomas (3.2-fold, P < .0001) and metastases (1.5-fold, P = .003). Moreover, in ER-negative breast cancers, nuclear AR-Ser(P)-650 was decreased (1.4-fold, P = .005), and cytoplasmic AR-Ser(P)-650 was increased (1.4-fold, P = .003).

CONCLUSIONS

AR and its phosphorylation at serines 213 and 650 are differentially expressed in breast cancer tumorigenesis and progression. Phosphorylation of AR at serines 213 and 650 is increased in ER-negative breast cancers, ductal carcinomas, and metastases and may have predictive value in breast cancer prognosis.